A distraught woman who drowned herself and three of her children by driving her minivan into the frigid waters of the Hudson River was studying to help children with emotional problems, her brother told ABCNews.com.

The sole survivor of the murder-suicide was the woman's 10 year-old son who was able to unroll a window and crawl out during the two minutes it took for the car to sink.

A soaking wet Leshaun Armstrong, 10, swam 25 yards in the cold and murky water as the van disappeared into eight feet of water behind him.

The boy was spotted by a passerby who took him to the fire house in Newburhg, N.Y/ where he told officials that his mother Leshanda Armstrong, 25, "intentionally drove the vehicle into the river," police said.

Armstrong, who relatives and neighbors praised for being an attentive mother, was studying social work at Orange County Community College and wanted to counsel children, her brother told ABCNews.com.

Now getting counseling for her son is a priority for her family.

"I talked to him last night," said Leshanda Armstrong's brother Ty'Mar Armstrong. "We'll look out for him. We'll help him. This is a dark time for him and my family."

Police said the car plunged into the water just 10 minutes after a police dispatcher got a 911 phone call from one of Armstrong's relatives reporting a "domestic argument" at the woman's house.

The relative called the home and overheard the fight, prompting the person call the police. When police arrived at Armstrong's home to investigate the call, no one was home.

Armstrong apparently loaded her four children in the car and drove it off a boat ramp around 7:50 p.m. in Newburgh, N.Y., a town about 60 miles north of New York City.

"All of the children were inside the vehicle, but the 10-year-old managed to escape," said Newburgh Police Chief Mike Ferrara. "He rolled down the window and climbed out before it sunk."

Leshawn was spotted by passerby Maevis Ryan who picked up the boy and drove him to the town's fire station.

He arrived at the fire house drenched and shivering, unable to clearly convey what had happened.

"When Leshaun came to the fire house he had difficulty speaking, he was repeating himself about the car in the water with his siblings… He was very shaken up and having a difficult time trying to explain what happened," said Fire Chief Michael Vatter.

"He was soaking wet. The river this year is about 40 to 45 degrees. He had a little hypothermia," he said.

The domestic dispute is believed to have been only a verbal argument with the father of Armstrong's three youngest children.

Police are interviewing the father, Jean Pierre. Police said the man did not live with the family and there was no record of previous disputes.

Armstrong's brother Ty'Mar Armstrong said the couple "had problems," but attributed their disputes to being young.

Ty'Mar Armstrong said his sister was a good mother who "was the best mother that you can ever see. She did positive things to make her kids happy. She would work to the bone to put the food on her children's plates and let them be happy."

The children who died in the van were identified as Landon Pierre, 5, Lance Pierre, 2, and Lainaina Pierre, 11 months old.

Police said all four children were alive when Armstrong drove the van into the river. Authorities said if not for Leshawn escaping police would have never know the van was in the river.